Wireless communications systems offer a variety of services to subscribers such as interconnect calling, short message service, packet data communications and dispatch communications. Many wireless communications systems facilitate communications between a wireless application server and a client application resident on the wireless subscriber unit. For example, dispatch services (also known as “push-to-talk” or “walkie-talkie” services) are currently offered as an Internet protocol (IP) application served by a dispatch server. Dispatch communication services are commonly implemented as a push-to-talk (PTT) type of service, such as the dispatch call service marketed by Sprint Nextel Corporation under the trade name Direct Connect.
While traditional mobile phone networks and devices utilize full-duplex communications, allowing subscribers to simultaneously talk and hear the other party, PTT communications are half-duplex meaning that communication proceeds in only one direction at a given time. Namely, PTT communications are initiated by a subscriber by first selecting target subscriber followed by pressing a so-called “PTT button” on their handheld device. The subscriber maintains the PTT button in the depressed position for as long as they want the “floor” (i.e., to be actively communicating to one or more other subscribers). Being a half-duplex communication, received audio is muted for the subscriber having the PTT floor. The initiating subscriber may then relinquish the PTT floor by releasing the PTT button. With the PTT floor now available, either the initiating or target subscriber may assume the floor by being the next to press their respective PTT buttons.
A PTT call can be either a group call or private call. Group calls involve simultaneous communication between more than two individuals who have all been assigned a common group identifier. Any group member may initiate or participate in their group's calls. With group calls, individuals initiate a group call by selecting the group name and pressing their handheld device's PTT button.
Private PTT calls, on the other hand, involve one-to-one communications. Moreover, there is no equivalent floor control functionality with private calls since the received audio is muted for the dispatch party having the floor. This is the case because the two subscribers are considered to be peers and pre-emption would not be acceptable from the user experience perspective. However, in certain contexts pre-emption would not interfere with the overall user experience and may be desirable to interrupt or otherwise assume the floor of a dispatch communication. As such, there is a need in the art to provide methods for PTT pre-emption in the private call context.